1. Field of the Invention
This invention relates to an exchangeable connecting device between a video camera and an automatic iris lens, especially an exchangeable connecting device arbitrary between video camera M and an automatic iris lens L having galvanometer control circuit p or an automatic iris lens L not having galvanometer control circuit p.
2. Description of the Prior Art
FIG. 4 shows a conventional connecting device between video camera M such as a CCD (Charged Couple Device) camera, an area image sensor and automatic iris lens L. Referring FIG. 4, an example of operational principal of automatic iris lens L and video camera M is explained.
A light signal passing through lens a is changed into electrical signal by area sensor b, amplified by AGC amplifier circuit c, processed by signal processing circuit d, and output as regular video signal IVpp.
On the other hand, a part of electrical signal of area sensor b is amplified by constant amplifier r of 6 dB to 12 dB and output as light control signal 1 for automatic iris lens L. Light control signal 1 is integrally amplified by level setting circuit e and provides driving DC current 2, for galvanometer f of iris control mechanism of automatic iris lens L. Variable resistor g is to set the iris value to a suitable value. Namely, DC current 2 increases according to an increase in light control signal 1 and closes iris I. On the contrary DC current 2 decreases according to a decrease in light control signal 1 and opens iris I, so that video camera M operates according to a suitable light control signal 1.
Normally, camera M needs various lens, therefore camera M and the lens are independent and according to necessity, connected by a thread.
On the other hand, information such as said light control signal 1 or driving DC current 2 are connected by a cable and connector.
However, there are two type of automatic iris lens L as follows;
1. VS (Video Signal) control type automatic iris lens L1.
This VS control type automatic iris lens L1 includes galvanometer control circuit p in which iris I is control by a part of light control signal 1 of a video signal.
FIG. 5 shows a connecting device of conventional video camera M1 and VS control type automatic iris lens L1 having galvanometer control circuit p and the same or similar numerals used for the same or similar parts of FIG. 4 and so on.
Video camera M1 and VS control type automatic iris lens L1 have connectors k, k connected by a cable (not shown) respectively connecting terminals {circle around (1)}, {circle around (2)}, {circle around (3)}, {circle around (4)} of connectors k, k. Terminal {circle around (1)} is connected to an electric circuit, terminals {circle around (2)}, {circle around (2)} are NC terminals (no connection), terminals {circle around (3)}, {circle around (3)} are connected to light control signal 1, terminals {circle around (4)}, {circle around (4)} are connected to ground (earth).
Operation of this circuit is as follows; light control signal 1 input from terminals {circle around (3)} is integral amplified by driving amplifier h, and video control signal 1 of video camera M1 set by variable resistor g reaches a level voltage corresponding to regular video signal IVpp, current in driving coil CL1 of galvanometer f decreases and controls iris I. Braking coil CL2 is to suppress rapid operation of driving coil CL1. Braking coil CL2 detects reverse voltage generated in galvanometer f, this reverse voltage is amplified in amplifier j, feedback to driving amplifier h, controls the movement of galvanometer f so as to be smooth and stable operation.
2. DC control type automatic iris lens L2.
This DC control type automatic iris lens L2 (FIG. 6) is intended to lower the lens price, which only includes galvanometer f and does not include galvanometer control circuit p (FIG. 5) and is driven by a suitable DC electric source from video camera M2.
FIG. 6 shows a connecting device of a conventional video camera M2 and DC control type automatic iris lens L2, without galvanometer control circuit p. As shown in FIG. 6, video camera M2 and DC control type automatic iris lens L2 have terminals of connectors k, k connected by a four wire cable (not shown) respectively, terminal {circle around (1)} of connectors k, k is connected to the positive (+) pole of braking coil CL2, terminal {circle around (2)}, is connected to the negative (xe2x88x92) pole of braking coil CL2, terminal {circle around (3)} is connected to the positive (+) pole of driving coil CL1, terminal {circle around (4)} is connected to the negative (xe2x88x92) pole.
Operation of this circuit is as follows; in video camera M2, video control signals 1 is integral amplified by driving amplifier h, changed into suitable driving DC current 2 set in variable resistor g, and drives driving coil CL1 through terminal {circle around (3)}, {circle around (4)} of connectors k, k.
Reverse voltage generated in braking coil CL2 is fed to video camera M2, through terminal {circle around (1)}{circle around (2)} as braking information.
Namely, this DC control type automatic iris lens L2 (paragraph heading xe2x80x9c2.xe2x80x9d above) eliminates galvanometer control circuit p (FIG. 5) against 1.VS control type automatic iris lens L1 so as to be simple in construction.
Therefore, to use this DC control type automatic iris lens L2 (described under heading xe2x80x9c2.xe2x80x9d above), it is necessary to provide galvanometer control circuit p in video camera M2.
However in actuality, it is desired to freely use said two kinds of lenses; of a VS control type automatic iris lens L1 (described under heading xe2x80x9c1xe2x80x9d above) or a DC control type automatic iris lens L, (described under heading xe2x80x9c2.xe2x80x9d above). And in actuality, connectors k, k used in said two kinds of VS control type automatic iris lens L, or DC control type automatic iris lens L, are the same in construction but connections are different.
FIG. 7 shows a circuit of a conventional exchangeable connecting device between video camera M3 and automatic iris lens L1 having galvanometer control circuit p or automatic iris lens L2 but not having galvanometer control circuit p.
Video camera M3 has two connectors k1and k2 one is for lens L1 and the other is for lens L2.
Terminal {circle around (3)} of connector k1 for lens L1 outputs video control signal 1 without galvanometer control circuit p. On the other hand, in connector k2, video control signal 1 is integral amplified by galvanometer control circuit p, changed into a suitable driving DC current 2, having its level set by variable resistor g so as to correspond to regular video signal IVpp and terminal {circle around (3)} of connector k2 for lens L2 and outputs driving DC current 2.
Therefore, the signal for controlling lens L1 and signal for controlling lens L2 are output from connector k1 and connector k2, respectively.
However, it is necessary to change the connector according to the lens being used and this is troublesome and can cause errors.
FIG. 8 shows a circuit of conventional general video camera M4, provided with switch v instead of two connectors for an exchangeable connection of lens L1 having galvanometer control circuit p or lens L2 without galvanometer control circuit p.
Namely, video control signals 1 and driving DC current 2 of galvanometer f are switched by switch v, and fed to common connector k. Other terminals are also switched.
However, it is necessary to change switch v according to the lens being used and this is troublesome and can cause errors.
Problems to be solved by this invention.
As explained above, in a conventional device, it is necessary to confirm the lens to be used and false connections of the connector or false switching can cause errors and damage of the device.
This invention intends to eliminate said drawbacks, and an object of this invention is to provide and exchangeable connecting device between a video camera and an automatic iris lens in which it is possible to use one common connector k to connect different kind of lenses. It is possible to use either kind of lens L1 or L2 without confirming the kind of lens to be used.
Claim 1 of this invention is to an exchangeable connecting device between video camera M5 (FIG. 2) such as a CCD (Charged Couple Device) camera, area image sensor and an automatic iris lens. In said video camera M5 one video control signal 1 is amplified the output of light sensor and directly connected to an analogue switch t, the other is connected through galvanometer control circuit p to analogue switch t, said analogue switch t being connected to one common connector k. When video signal control type automatic iris lens L1 is connected to connector k, video control signal 1 amplified the output of light sensor, is directly connected to analogue switch t and common connector k. When a DC control type automatic iris lens L2, said analogue switch t is switched and video control signal 1 is amplified by said galvanometer control circuit p, so that the output of the light sensor is connected to connector k as control current 2 of galvanometer f corresponding to video signal LVpp.
Claim 2 of this invention, a detecting circuit of an exchangeable connecting device between video camera M5 and automatic iris lens as claimed in claim 1, detects a variation of voltage or current at terminals of connector k according to the connection of a video signal control type automatic iris lens L1 or DC control type automatic iris lens L2.
Claim 3 of this invention, is an exchangeable connecting device between video camera M5 and automatic iris lens as claimed in claim 1, in which mechanical switch v1, is used instead of said analogue switch t.
Claim 4 of this invention, an exchangeable connecting device between video camera M6 and an automatic iris lens as claimed in claim 1. In said video camera M6; one of said video control signals 1 is connected through an interfere preventing element to one common connector k and the other is connected to galvanometer control circuit p to said one common connector k. When VS control type automatic iris lens L1 is connected to connector k, video control signals 1 is connected through an interfere preventing element to one common connector k. When DC control type automatic iris lens L2, and video control signals 1 is connected to one common connector k driving DC current 2 of video camera M6 is integral amplified by galvanometer control circuit p.